WASHINGTON (CNN) -- Five former Blackwater security guards, indicted in a 2007 shooting incident in Baghdad that left 17 Iraqis dead, will surrender to the FBI on Monday, a source told CNN on Saturday.
An Iraqi woman looks at a blood-stained car of two women killed in the 2007 Nusoor Square shooting.
The men were identified as Donald Ball, 26, of West Valley City, Utah; Dustin Heard, 27, of Knoxville, Tennessee.; Evan Liberty, 26, of Rochester, New Hampshire; Nick Slatten, 25, of Sparta, Tennessee; and Paul Slough, 29, of Keller, Texas. All have served in the military.
Two people with knowledge of the case said Friday that a sixth security guard is in plea negotiations.
The exact charges handed up by a federal grand jury this week were not revealed, because the indictment remains under court seal. It could be made public by Justice Department officials Monday.
Sources have said that charges under consideration included murder and assault.
The Justice Department had no comment on the development Friday. The State Department, which employed Blackwater to protect U.S. diplomats and other employees, also had no comment. Blackwater declined to comment until an official announcement is made.
Blackwater Worldwide has been told by the government that the company will not face charges, according to several sources.
"We strongly disagree with the Department of Justice's decision to bring charges against Dustin Heard," attorney David Schertler said in a statement. "Any charges brought against Mr. Heard are wrong and unjust."
Slough's attorney, Mark Hulkower, said he is "an honorable young man who served this country with distinction for many years."
CNN was attempting to contact attorneys for the other men Saturday.
The six guards were informed during the summer that they were targets of the investigation into the September 16, 2007, shooting in a Baghdad intersection.
Blackwater claims that its employees were returning fire after coming under attack from insurgents, but an Iraqi investigation called the killings "premeditated murder."
None of the guards has worked for Blackwater since 2007, company spokeswoman Anne Tyrrell said.
"On September 16, 2007, at Nisour Square, Blackwater security guards were defending themselves and their comrades who were being shot at and receiving fire from Iraqis they believed to be enemy insurgents, in a place where the enemy has made a major city, Baghdad, the battlefield," Schertler said. "Because of that and because of the deceptive tactics used by these insurgents against Americans, civilian casualties tragically occur.
"We have been and remain determined and prepared to fight these charges, and we are confident that Dustin Heard will be vindicated."
The complex legal case has been dogged by difficulties and may present a major challenge to federal prosecutors.
Among the potential problems is that the law under which the charges are expected to be brought covers contractors working for the U.S. military, but the Blackwater guards were contracted by the State Department. Some independent legal experts have questioned whether U.S. courts would have jurisdiction in this type of case.
Also muddying the case are assurances of immunity initially given to the guards by State Department Diplomatic Security Agents, who were investigating the incident before the FBI tried to interview them when it took over the investigation.
The State Department maintains that its agents did not offer blanket immunity from criminal prosecution but only promised that the statements the guards made on the scene could not be used against them in any prosecution.
But when the investigation was turned over to the Justice Department to examine possible criminal activity, FBI agents discovered that some guards believed they were immune from prosecution and therefore refused to be interviewed again, complicating the FBI investigation.
The indictments come within days of a new U.S.-Iraq Status of Forces Agreement, which pointedly specifies that U.S. civilian contractors will no longer be immune from Iraqi prosecution for crimes committed in that country.
The State Department renewed Blackwater's contract this year over strong objections from the Iraqi government.
CNN's Terry Frieden and Elise Labott contributed to this report.